Some of the riskiest decisions that youths make concern alcohol use: how to drink, with whom to drink, at what age to begin drinking, what to do (e.g., drive, take other drugs) after consuming alcohol. As long as youths have some discretion to make such decisions, their success in managing those risks will depend on their understanding of their magnitude. Understanding how youths think about the nature and magnitude of risks is the focus of this proposal. It outlines a series of empirical studies designed initially to develop a comprehensive methodology for assessing adolescents' risk perceptions, followed by applications of methodology to study how diverse groups of youths think about particular risks, with a focus on alcohol consumption and abuse. These results are then applied to secondary analyses of earlier studies to risk perceptions (in order to examine the clarity of their questions) and of typical health risk communications (in order to examine their appropriateness to the risk conceptualizations of the youths to whom they are directed). The ultimate goals of the project are to determine what adolescents believe regarding the risks associated with particular risk behaviors, how these beliefs may be related to their own risk behavior, and how risk communications regarding those risks might be made more effective in terms of providing the information that teenagers need to judge the magnitude of the risks they face.